This invention relates to an amphibious vehicle, and particularly to a vehicle having ground wheels that can be raised or lowered, whereby the vehicle can be operated in water or on land.
Amphibious vehicles of various types are already well known in the art. For example, Baradi, U.S. Pat. No. 5,181,478 discloses an amphibious vehicle includes a hull having five wheels along each of its sides. The wheels can be retracted into cavities in the hull side walls by means of hydraulic cylinders. Each set of wheels is driven by a hydraulic motor, so that the vehicle can be steered by adjusting the relative speeds of the motors. The wheels on each side of the vehicle are linked together by drive chains, whereby all wheels on a given side of the hull rotate at the same speed.
Seligman, et al., U.S. Pat. No. 5,199,372 discloses an amphibious vehicle having two pair of wheels located along the side walls of a hull. Elevator mechanisms within the hull enable the wheels to be raised or lowered, whereby the vehicle can be supported in the water or on the land.
Doyon, U.S. Pat. No. 5,400,734 discloses an amphibious vehicle having a chassis located above three endless tread-type tracks, whereby the vehicle is enabled to climb out of the water onto a bank at the water's edge. Each track is driven by a hydraulic motor. Movement on dry land is accomplished by auxiliary wheels located alongside the tracks in operative connection to the hydraulic motors. Movement in the water is accomplished by an outboard motor.
The amphibious vehicle of the present invention utilizes a relatively simple wheel arrangement comprising only three ground wheels. There is a single front wheel that is steerable, and two rear wheels that are non-steerable. Each rear wheel is driven by a separate hydraulic motor, connected in a parallel hydraulic circuit which provides a differential for ease of turning the vehicle.
The single front wheel can be shifted between a retractable inactive position within a well in the bow of the vehicle hull and an exposed operative position extending below the hull. The wheel shifting mechanism has a telescopic feature that enables the front wheel to have relatively good ground clearance when it is in the operative position. The front wheel is stored in a relatively small size compact space in the well when it is in its retracted position.
Each rear wheel is suspended from the hull by means of a lever that is swingable on an axis that parallels the hull longitudinal axis, whereby each rear wheel can have an elevated retracted position above the waterline or a lowered operating position below the hull. Each rear wheel carries a hydraulic motor rigidly attached to the terminal end of the aforementioned wheel suspension lever, whereby the motors are at all times in operative connection to the respective rear wheels.
Each wheel suspension lever preferably comprises a hollow tubular structure of sufficient internal diameter to act as a conduit for the hydraulic hoses that supply pressurized hydraulic fluid to the associated motors. The hydraulic hoses are carried within the hollow tubular levers so that no additional openings or seals are needed in the stern to the external hydraulic motors. This feature somewhat simplifies the hydraulic system, while avoiding potential leakage points that could exist if the hydraulic hoses were routed in some other fashion.
Preferably each hollow tubular lever includes an elongated linear tube section extending through spaced bearings in the hull. The front end of each elongated linear tube section is captured fore and aft of the bearing to transmit forward and reverse thrust forces from the wheels to the hull.
A principal aim of the invention is to provide a relatively simple retractable wheel arrangement that utilizes an essentially standard commercially available hull having high performance in the water. A related aim is to provide the retractable wheel features without requiring extensive modification or redesign of the commercially available hull.